Molecular Identification And Population Dynamics Of The Major Malaria Vectors In A Rainforest Zone Of Nigeria

Adult female mosquito vectors were collected from three villages in a typical rain forest area of Nigeria where no information exists on the major malaria vectors associated with human malaria. Sampling was carried out between January 2004 and January 2005 using pyrethrum and Human landing catch (HLC) techniques. A total catch of 2010 mosquitoes was recorded out of which 1800 were morphologically identified as female Anopheline mosquitoes. Further identification of the Anopheline species using the morphological keys revealed that 1399 (77.7%) belonged to the Anopheles gambiae s.l. and 401 (22.3%) to Anopheles funestus . A PCR based test on the Anopheles gambiae group identified 636 (45.5%) as Anopheles gambiae s.s and 763 (54.5%) as Anopheles arabiensis respectively. The cocktail PCR-assayon the total Anopheles funestus group showed 307 (76.6%), to be Anopheles funestus s.s and 94 (23.4%) to be Anopheles leesoni . The total number of Anopheles gambiae collected across the 3 villages was significantly higher (P<0.05) than the number of Anopheles funestus caught within the same period. However, there was a seasonal difference in the population of Anopheline species collected in which the wet season collections constitute 45.4% An.gambiae s.l and 17.7% An.funestus while the dry season population constitutes 32.3% An.gambiae s.l and 4.5% An.funestus. The dry seasoncollections were predominantly An. arabiensis producing 23.9% of the total catch in.The overall number of Anopheles mosquitoes collected in the wet season was significantly higher than that of the dry season (P<0.01). Generally, low sporozoite rates were recorded in all the communities and this may be an indication that transmission in this area is less intense. This study provides information on mosquito ecology, genetic and molecular techniques for identification of species complexes which are important strategies for planning malaria control programmes

DNA barcoding of Tribolium castaneum (Coleoptera: Tenebrionidae) from selected states in Nigeria based on mitochondrial DNA sequences

Tribolium castaneum also known as red flour beetle is one of the most important pests of stored grain product with a cosmopolitan distribution in Nigeria and all over the world contributing to food spoilage. The aim of this study was to characterize the T. castaneum by morphometric and molecular analyses. Samples of yam flour with evidence of the red flour beetles present inside were obtained from four locations in Kwara, Kogi, Oyo and Ekiti states in Nigeria. Morphological and molecular identifications of T. castaneum were carried out using standard methods. A dissecting microscope was used to identify the beetles and measurements were taken using ImageJ. Genomic DNA was extracted and checked on 1.5% agarose gel to confirm the presence of DNA. Species-specific primers were used to amplify mitochondrial cytochrome oxidase I (COI) gene of T. castaneum and the PCR amplicon size was also checked on 1.5% agarose. Morphometric measurements showed that the highest mean number (33.00±4.24 mm) of T. castaneum larvae observed was recorded on day 61 in Ilorin and the lowest was in Iwo, Osun state (4.00±0.00 mm) on the same day. The mean of the total body length of larvae from sampling sites was (1.31±0.37 mm) with minimum and (1.63±1.14 mm) maximum lengths respectively. There was no significant difference (p>0.05) between the mean length of the larvae collected from the study locations. Aligned cytochrome oxidase subunit 1 (COI) sequences of 313bp were analyzed. Phylogenetic analysis inferred by maximum likelihood method showed that the T. castaneum sequences analyzed for this study and sequences obtained from GenBank formed a monophyletic group. The molecular and phylogenetic analyses confirmed the presence of a single species of T. castaneum. The results from this study showed low levels of genetic diversity and variability in the studied T. castaneum populations. The observed genetic similarity in T. castaneum could be due to the fact that they were probably from similar origin when compared with those in the GenBank database. However, further studies are needed with more samples to characterize T. castaneum species from stored food grains across Nigeria

Genetic Diversity of West African Honey Bee (Apis ‎mellifera adansonii Latreille, 1804) from Rural and Urban ‎Areas of ‎Kwara State, North-Central Nigeria

Over one third of the world’s crops– including fruits, vegetables, nuts, spices, and oilseed–‎require insect pollination, and human reliance on ‎pollination services by honey bees (Apis ‎mellifera) to promote these crops continues to rise due to increasing demands from growing ‎human ‎populations. Identifying the effects of urbanization on genetic diversity on this ‎pollinating insect is important in the field of bioscience. This study aimed to investigate genetic diversity of A. mellifera in Kwara State, Nigeria, using the random amplified polymorphic DNA (RAPD) marker. ‎Thirty honey bees ‎were simultaneously collected from both rural and urban regions in ‎Kwara state, Nigeria. Samples were morphologically identified using ‎standard methods, ‎genomic DNA isolated and amplified using five RAPD primers. Data collected were ‎analysed using PyElph, ‎ARLEQUIN, and GeneAlEx version 6.501 software. The results ‎showed that the DNA fragment sizes produced per primer varied from 200 to ‎‎3000 bp. Percentages of polymorphic loci amplified by each primer varied from 17.33 to 33.33%. ‎Analysis of unbiased Nei genetic ‎distance values showed that Agbede (rural) and Adewole ‎‎(urban) showed the highest value of unbiased genetic distance (0.073), while ‎Amoyo ‎‎(rural) to Idofian (urban) exhibited the lowest value (0.027). Dendrogram analysis revealed ‎genetically close relationships among the sampled ‎A. mellifera‎ populations. The low level of genetic ‎polymorphisms observed among the honey bee populations in the two ‎regions ‎indicated that there is genetic relatedness among them. This study concluded that RAPD ‎marker is a useful method for ‎understanding population genetic structure of the African honey ‎bees. These results can be used as baseline information for future genetic ‎diversity ‎assessment of honey bees in Nigeria with larger samples. It is therefore recommended that ‎there is a need to safeguard the genetic ‎diversity of A. mellifera‎ to prevent extinction or ‎gradual loss of diversity‎‎‎.    

Mind the weather: a report on inter-annual variations in entomological data within a rural community under insecticide-treated wall lining installation in Kwara State, Nigeria

Abstract Background Entomological indices within a specific area vary with climatic factors such as rainfall, temperature and relative humidity. Contributions of such weather parameter fluctuations to the changes in entomological data obtained within a community under implementation of a promising vector control intervention should be taken into account. This study reports on inter-annual changes in entomological indices within two rural communities, one of which was under insecticide-treated durable wall lining (DL) installation. Methods Community-wide DL installation was followed by monthly meteorological data and pyrethrum spray mosquito collections for 2 years in intervention and a similar neighbouring community (control). Human blood meal and sporozoite ELISA tests were conducted on female mosquitoes collected alongside PCR identification of subsamples. Mosquitoes collected at the intervention site were tested in cone susceptibility assays against subsamples of installed DL materials collected on a 6-monthly basis for 2 years. Deltamethrin susceptibility of Anopheles mosquitoes from the intervention site was determined before and after DL installation. Entomological indices in the first and second years were compared within each site. Results Rainfall in the study area increased significantly (t = -3.45, df = 11, P = 0.005) from first to second year. Correlation between rainfall and Anopheles densities in both sites were significant (r = 0.681, P < 0.001). Mosquitoes collected at the intervention site were susceptible (100%) to deltamethrin at baseline but resistant (92%) in the second year. However, subsamples of installed DL materials remained effective (100% mortality) against Anopheles mosquitoes from the intervention site throughout the 6-monthly cone assay exposures. Monthly pyrethrum spray collections showed significant increase in Anopheles densities from first to second year in the control (6.36 ± 1.61 vs 7.83 ± 2.39; t = -3.47, df = 11, P = 0.005), but not in the intervention (2.83 ± 1.86 vs 4.23 ± 3.31; t = -2.03, df = 11, P = 0.067) community. However, mean annual mosquito man-biting rates increased significantly in both intervention (0.88 ± 0.18 vs 1.06 ± 0.38; F (1, 10) = 9.50, P = 0.012) and control (1.45 ± 0.31 vs 1.61 ± 0.34; F (1, 10) = 10.18, p = 0.010) sites along with increase (≥ 1.6 times) in sporozoite rates within intervention (0–2.13%) and control (2.56–4.04%) communities. Conclusions The slight increase in vector density, induced by significant increase in rainfall, led to increased sporozoite infection and significantly increased man-biting rates within the intervention site. These reveal the need for incorporation of integrated vector management strategies to complement DL installation especially in regions with high rainfall and mosquito density. Promising vector control tools such as DL should be evaluated on a long-term basis to reveal the possible effect of weather parameters on control performance and also allow for holistic recommendations

Molecular identification and population dynamics of the major malaria vectors in a rainforest zone of Nigeria

Adult female mosquito vectors were collected from three villages in a typical rain forest area of Nigeria where no information exists on the major malaria vectors associated with human malaria. Sampling was carried out between January 2004 and January 2005 using pyrethrum and Human landing catch (HLC) techniques. A total catch of 2010 mosquitoes was recorded out of which 1800 were morphologically identified as female Anopheline mosquitoes. Further identification of the Anopheline species using the morphological keys revealed that 1399 (77.7%) belonged to the Anopheles gambiae s.l. and 401 (22.3%) to Anopheles funestus. A PCR based test on the Anopheles gambiae group identified 636 (45.5%) as Anopheles gambiae s.s and 763 (54.5%) as Anopheles arabiensis respectively. The cocktail PCR-assay on the total Anopheles funestus group showed 307 (76.6%), to be Anopheles funestus s.s and 94 (23.4%) to be Anopheles leesoni. The total number of Anopheles gambiae collected across the 3 villages was significantly higher (

Outcome of capacity building intervention for malaria vector surveillance, control and research in Nigerian higher institutions

Abstract Background Despite the availability of effective malaria vector control intervention tools, implementation of control programmes in Nigeria is challenged by inadequate entomological surveillance data. This study was designed to assess and build the existing capacity for malaria vector surveillance, control and research (MVSC&R) in Nigerian institutions. Methods Application call to select qualified candidates for the capacity building (CB) intervention training programme was advertised in a widely read newspaper and online platforms of national and international professional bodies. Two trainings were organized to train selected applicants on field activities, laboratory tools and techniques relevant to malaria vector surveillance and control research. A semi-structured questionnaire was administered to collect data on socio-demographic characteristics of participants, knowledge and access of participants to field and laboratory techniques in MVSC&R. Similarly, pre and post-intervention tests were conducted to assess the performance and improvement in knowledge of the participants. Mentoring activities to sustain CB activities after the training were also carried out. Results A total of 23 suitable applicants were shortlisted out of the 89 applications received. The South West, South East and North Central geopolitical zones of the country had the highest applications and the highest selected number of qualified applicants compared to the South South and North East geopolitical zones. The distribution with respect to gender indicated that males (72.7%) were more than females (27.3%). Mean score of participants’ knowledge of field techniques was 27.8 (± 10.8) before training and 67.7 (± 9.8) after the training. Similarly, participants’ knowledge on laboratory techniques also improved from 37.4 (± 5.6) to 77.2 (± 10.8). The difference in the mean scores at pre and post-test was statistically significant (p < 0.05). Access of participants to laboratory and field tools used in MVSC&R was generally low with insecticide susceptibility bioassays and pyrethrum spray collection methods being the most significant (p < 0.05). Conclusions The capacity available for vector control research and surveillance at institutional level in Nigeria is weak and require further strengthening. Increased training and access of personnel to relevant tools for MVSC&R is required in higher institutions in the six geopolitical zones of the country

Evidence of carbamate resistance in urban populations of <it>Anopheles gambiae s.s.</it> mosquitoes resistant to DDT and deltamethrin insecticides in Lagos, South-Western Nigeria

<p>Abstract</p> <p>Background</p> <p>Resistance monitoring is essential in ensuring the success of insecticide based vector control programmes. This study was carried out to assess the susceptibility status of urban populations of <it>Anopheles gambiae</it> to carbamate insecticide being considered for vector control in mosquito populations previously reported to be resistant to DDT and permethrin.</p> <p>Methods</p> <p>Two – three day old adult female <it>Anopheles</it> mosquitoes reared from larval collections in 11 study sites from Local Government Areas of Lagos were exposed to test papers impregnated with DDT 4%, deltamethrin 0.05% and propoxur 0.1% insecticides. Additional tests were carried out to determine the susceptibility status of the <it>Anopheles gambiae</it> population to bendiocarb insecticide. Members of the <it>A. gambiae complex</it>, the molecular forms, were identified by PCR assays. The involvement of metabolic enzymes in carbamate resistance was assessed using Piperonyl butoxide (PBO) synergist assays. The presence of kdr-<it>w/e</it> and ace-1R point mutations responsible for DDT-pyrethroid and carbamate resistance mechanisms was also investigated by PCR.</p> <p>Results</p> <p>Propoxur resistance was found in 10 out of the 11 study sites. Resistance to three classes of insecticides was observed in five urban localities. Mortality rates in mosquitoes exposed to deltamethrin and propoxur did not show any significant difference (P > 0.05) but was significantly higher (P < 0.05) in populations exposed to DDT. All mosquitoes tested were identified as <it>A. gambiae s.s</it> (M form). The <it>kdr -w</it> point mutation at allelic frequencies between 45%-77% was identified as one of the resistant mechanisms responsible for DDT and pyrethroid resistance. <it>Ace-1R</it> point mutation was absent in the carbamate resistant population. However, the possible involvement of metabolic resistance was confirmed by synergistic assays conducted.</p> <p>Conclusion</p> <p>Evidence of carbamate resistance in <it>A. gambiae</it> populations already harbouring resistance to DDT and permethrin is a clear indication that calls for the implementation of insecticide resistance management strategies to combat the multiple resistance identified.</p